Difference between Unique Indexes and Unique Constraints in SQL Server

ORA-00001 unique constraint violated – Oracle PL/SQL Tutorial

Constraints in SQL Server: SQL NOT NULL, UNIQUE and SQL PRIMARY KEY

💡 SQL Interview Question: 👉 How do you add a PRIMARY KEY constraint to an existing table in SQL? This is a frequently asked SQL interview question to test your understanding of constraints and table modification. Here’s the clean SQL query 👇 ALTER TABLE employees ADD CONSTRAINT pk_employees PRIMARY KEY (employee_id); 🎯 Explanation: ALTER TABLE is used to modify an existing table ADD CONSTRAINT defines a new table constraint pk_employees is the name of the primary key constraint employee_id b

To remove an attribute or to add a constraint to an already existing table we use: | Shaalaa.com

Adding A Check Constraint

Foreign Key vs Primary Key - What is the Difference? - Essential SQL

Surrogate Key vs Natural Key Differences and When to Use in SQL Server

Auto generated SQL Server keys uniqueidentifier or IDENTITY